"An injection that prevents breast cancer is being developed by scientists," is the exciting news on the Mail Online website. The injection uses small packets of RNA to "shut down" the genes inside cancerous cells…

"'An injection that prevents breast cancer is being developed by scientists," is the news on the Mail Online website.

This news seems a heartening way to start the year, but a caveat is that the research is in the very early stages – as yet only tested in mice.

The researchers were interested in a type of breast cancer known as ductal carcinoma in situ (DCIS).

In DCIS the cancerous cells are contained within the ducts in the breast, and not spread to other breast tissue. The problem with DCIS is that it is currently impossible to predict whether the cancer will remain inside the duct (so will not require treatment) or become invasive and spread into other parts of the breast. This means that some women with DCIS will undergo invasive treatment unnecessarily.

This research involved genetically engineered mice designed to develop DCIS-like tumours that eventually spread. They found that a gene called Hox1A seemed to be involved in stimulating the growth of the DCIS-like tumours. They then went on to use an injection of specially designed nanoparticles into the mammary tissue, designed to "turn-off" the Hox1A gene.

They found that the injection stopped three-quarters of the mice from developing tumours at 21 weeks. However, the researchers don’t yet know if the tumours might develop later in these mice, or are stopped completely.

These findings are definitely worth more investigation, but, as yet, implications for human breast cancer prevention or treatment are still uncertain.

Nanotechnology

This research made use of nanotechnology: the manipulation of very, very small amounts of matter; in other words using extremely small tools.

Nanoparticles are extremely small particles, and these are being put to a variety of different uses. Over 100,000 nanoparticles could fit on the full stop at the end of this sentence.

Where did the story come from?

The study was carried out by researchers from Harvard University and other research institutions in the US. It was funded by the US Department of Defense and the Wyss Institute for Biologically Inspired Engineering. The study was published in the peer-reviewed journal Science Translational Medicine.

The Mail Online’s headline and photos of women (including Angelina Jolie) may lead people to believe that this research is more advanced than it is. As yet, this technique has only been tested in mice, so its effects in humans are not known.

So despite the Mail Online’s claims, it is far too early to know whether it will “spare thousands of women the trauma of surgery”. (The injection was also not given intravenously as the Mail Online suggests, it was injected directly into the mice’s mammary tissue.)

What kind of research was this?

This was laboratory and animal research aiming to understand more about which genes are involved in the development of breast tumours and to see if blocking these genes could stop tumour progression.

This early stage research was carried out mainly in mice, but researchers hope that their findings will be applicable in humans. The genetically engineered mice they used start to show abnormal mammary cells at about 12 weeks of age, before developing growths that are contained within the mammary glands at about 16 weeks, and then progress to invasive tumours at 20 weeks of age.

At the point where the growths are contained within the mammary glands, they resemble ductal carcinoma in situ (DCIS) in humans. DCIS is a very early stage of breast cancer where there are abnormal cancer cells in the breast ducts, but the cancer has not spread out into the breast tissue. It is estimated that up to half of people with DCIS will go on to develop invasive breast cancer. This is where the cancer has spread into the breast tissue with potential for spread to the lymph nodes and other tissues and organs of the body. In the remainder of people the abnormal cells will remain confined to the breast ducts and they will never develop invasive breast cancer.

The difficulty for scientists and medical professionals is that they can’t tell in advance whether DCIS will progress to invasive cancer or will be the non-aggressive kind that remains confined to the ducts. So currently all women with DCIS are assumed to be at risk of invasive breast cancer and are offered treatment as a precaution, such as surgery or radiation. Doctors would like to be able to use less invasive treatments for DCIS that would still be effective, and also have fewer side effects. The current research aimed to test an approach that could eventually provide a way to do this.